Current operation of surveillance and reconnaissance aircraft requires radio equipment to transmit moving television camera and radar images through antennas mounted on the aircraft to antennas and suitable receivers on other aircraft or on ground units or on spacecraft. The transmitting aircraft which may retransmit or relay signals received from other sources, may be unmanned aircraft capable of remaining on station for many hours. The transmissions are normally organised as point to point transactions. Broadcast transmission from the aircraft is also used when multiple users require the same information simultaneously. In certain locations and operations the bandwidth available for radio or telephony transmission of the images is severely constrained. If more than a single channel of point to point transmission is required the electromagnetic bandwidth utilisable is further constrained. This may require restraint within internationally agreed radio bands and restraint when required to operate over undulating terrain that might inhibit line of sight transmission.
Transmission of broadband (wideband) video signals can be carried out by fibre-optic telephone lines. These possess sufficient bandwidth to carry multiple television channels but may be fragile or difficult to install in some locations. Otherwise telephony is mainly restricted to low bandwidth information and intermittent image frames.
Television signals may be transmitted via orbiting satellites which is good for distributing multiple television channels but with a high cost of ownership and high use costs. Additionally access to the satellites may not be under the control of the user.